How much is the finished plane supposed to weigh? If it comes in weighing no more than 4.5 pounds and at least 600 sq inches, a standard .40-.46 will fly it with some gusto but it wont be a show stopper. Even with a strong .45-.50 like a Rossi or Webra, 4.5 pounds is the upper limit for anything ressembling 3D. A well set up profile with low wing loading and ample power is difficult to stall, making it a good choice for a 2nd plane. I wish they had come out sooner instead of wasting much of my learning years flying mediocre, run of the mill kind of stuff.